scholarly journals Effect of neutral winds on the creation of non-specular meteor trail echoes

2020 ◽  
Author(s):  
Freddy Galindo ◽  
Julio Urbina ◽  
Lars Dyrud
Keyword(s):  
Time Delays ◽  
Dense Plasma ◽  
Plasma Instabilities ◽  
Vhf Radar ◽  
Neutral Winds ◽  
Physical Conditions ◽  
Temporal Space ◽  
Meteor Trail ◽  
The Right ◽  
Field Aligned Irregularities

Abstract. Non-specular meteor trail echoes are radar reflections from plasma instabilities that are caused by field-aligned irregularities. Meteor simulations are examined to show that these plasma instabilities, and thus the associated meteor trail echo, strongly depend on the meteoroid properties and the characteristics of the atmosphere in which the meteoroid is embedded. The effects of neutral winds, as a function of altitude, are analyzed to understand how their amplitude variability impacts the temporal-space signatures of non-specular meteor trail echoes present in VHF radar observations. It is found that amplitudes of the total horizontal neutral wind smaller than 0.6 m/s do not provide the right physical conditions to enable the genesis of non-specular meteor echoes. It is also found that a 0.0316 μg meteoroid traveling at 35 km/s can be seen as a meteor trail echo if the amplitudes of horizontal neutral winds are stronger than 15 m/s. In contrast, a 0.316 μg meteoroid, traveling at the same speed, requires horizontal winds stronger than 1 m/s to be visible as a meteor trail echo. The meteor simulations also indicate that time delays on the order of hundreds of milliseconds or longer, between head-echoes and non-specular echoes, which are present in VHF backscatter radar maps can be a consequence of very dense plasma trails being affected by weak horizontal neutral winds that are smaller than 1 m/s.

scholarly journals Effect of neutral winds on the creation of non-specular meteor trail echoes

2021 ◽  
Vol 39 (4) ◽  
pp. 709-719
Author(s):  
Freddy Galindo ◽  
Julio Urbina ◽  
Lars Dyrud
Keyword(s):  
Plasma Instabilities ◽  
Very High Frequency ◽  
Vhf Radar ◽  
Radar Observations ◽  
Neutral Winds ◽  
Physical Conditions ◽  
Temporal Space ◽  
Meteor Trail ◽  
Meteor Trails ◽  
The Right

Abstract. Non-specular meteor trail echoes are radar reflections from plasma instabilities that are caused by field-aligned irregularities. Meteor simulations are examined to show that these plasma instabilities, and thus the associated meteor trail echo, strongly depend on the meteoroid properties and the characteristics of the atmosphere in which the meteoroid is embedded. The effects of neutral winds, as a function of altitude, are analyzed to understand how their amplitude variability impacts the temporal–space signatures of non-specular meteor trail echoes present in very high-frequency (VHF) radar observations. It is found that amplitudes of the total horizontal neutral wind smaller than 0.6 m s−1 do not provide the right physical conditions to enable the genesis of non-specular meteor echoes. It is also found that a 0.0316 µg meteoroid traveling at 35 km s−1 can be seen as a meteor trail echo if the amplitudes of horizontal neutral winds are stronger than 15 m s−1. In contrast, a 0.316 µg meteoroid, traveling at the same speed, requires horizontal winds stronger than 1 m s−1 to be visible as a meteor trail echo. The neutral velocity threshold illustrates how simulations show that no trail echo is created below a critical wind value. This critical wind value is not mapped directly to radar observations, but it is used to shed light on the physics of meteor trails and improve their modeling. The meteor simulations also indicate that time delays on the order of hundreds of milliseconds or longer, between head echoes and non-specular echoes, which are present in VHF backscatter radar maps, can be a consequence of very dense plasma trails being affected by weak horizontal neutral winds that are smaller than 1 m s−1.

scholarly journals First simultaneous lidar observations of sodium layers and VHF radar observations of E-region field-aligned irregularities at the low-latitude station Gadanki

2009 ◽  
Vol 27 (9) ◽  
pp. 3411-3419 ◽  
Author(s):  
S. Sridharan ◽  
A. K. Patra ◽  
N. Venkateswara Rao ◽  
G. Ramkumar
Keyword(s):  
Lower Thermosphere ◽  
Low Latitude ◽  
Vhf Radar ◽  
Neutral Winds ◽  
Zonal Winds ◽  
Tidal Phase ◽  
E Region ◽  
The Relationship ◽  
Lidar Observations ◽  
Field Aligned Irregularities

Abstract. Simultaneous observations of atmospheric sodium (Na) made by a resonance lidar and E-region field-aligned-irregularities (FAI) made by the Indian MST radar, both located at Gadanki (13.5° N, 79.2° E) and horizontal winds acquired by a SKiYMET meteor radar at Trivandrum (8.5° N, 77° E) are used to investigate the relationship among sodium layer, FAI and neutral winds in the mesosphere and lower thermosphere region. The altitudes and descent rates of higher altitude (~95 km) Na layer and FAI agree quite well. The descending structures of the higher altitude Na layer and FAI are found to be closely related to the diurnal tidal phase structure in zonal winds observed over Trivandrum. At lower altitudes, the descent rate of FAI is larger than that of Na layer and zonal tidal phase. These observations support the hypothesis that the metallic ion layers are formed by the zonal wind shear associated with tidal winds and subsequently get neutralized to manifest in the form of descending Na layers. The descending FAI echoing layers are manifestation of the instabilities setting in on the ionization layer. In the present observations, the altitudes of occurrence of Na layer and FAI echoes being low, we surmise that it is quite possible that the FAI echoes are due to the descent of already formed irregularities at higher altitudes.

Effects of Menopausal Symptoms on Work Life and Organizational Environment.

2020 ◽  
Vol 16 ◽  
Author(s):  
Aslı Eker ◽  
Meltem Aydın Besen ◽  
Mine Yurdakul
Keyword(s):  
Work Performance ◽  
Work Life ◽  
Working Environment ◽  
Detailed Knowledge ◽  
Physical Conditions ◽  
Negative Effect ◽  
Perceived Effects ◽  
Study Population ◽  
Policies And Programs ◽  
The Right

Background: Every working woman has the right to continue to live as a healthy individual. The working environment has important effects on general health status and reproductive health of women. If menopouse period of women is not taken into consideration and if appropriate arrangements are not made at workplaces, their work performance and productivity decrease. It is important to have detailed knowledge about factors creating risk for health in order to develop effective policies and programs directed towards preventing them. Objective: This study was performed to determine perceived effects of menopause on work life and attitudes of an institution towards menopausal women. Methods: The study population included 419 women aged 45-55 years and working at a university. Out of 419 women, 291 could be contacted. Data were collected with a questionaire composed of questions about descriptive characteristics, effects of menopause on work life and support from and attitudes of the institution about menopause. Data collected to reveal menopausal women’s experiences at work were analyzed with statistical methods frequency, percentages and mean. Results: The mean age at which menopause started was 47 years and 89.7% of the women experienced menopausal complaints. Conclusions: Physical conditions at work and stressors were found to increase menopausal complaints and had a negative effect on work performance.

scholarly journals Simultaneous VHF radar backscatter and ionosonde observations of low-latitude E region

2005 ◽  
Vol 23 (3) ◽  
pp. 773-779 ◽  
Author(s):  
A. K. Patra ◽  
S. Sripathi ◽  
P. B. Rao ◽  
K. S. V. Subbarao
Keyword(s):  
Low Latitude ◽  
Vhf Radar ◽  
Radar Echoes ◽  
First Results ◽  
E Region ◽  
Gradient Drift ◽  
Drift Instability ◽  
Relationship Of ◽  
The Relationship ◽  
Field Aligned Irregularities

Abstract. The first results of simultaneous observations made on the low-latitude field-aligned irregularities (FAI) using the MST radar located at Gadanki (13.5° N, 79.2° E, dip 12.5°) and the Es parameters using an ionosonde at a nearby station Sriharikota (13.7° N, 80.1° E, dip 12.6°) are presented. The observations show that while the height of the most intense radar echoes is below the virtual height of Es (h'Es) during daytime, it is found to be either below or above during nighttime. The strength of the FAI is better correlated with the top penetration frequency (ftEs) and the blanketing frequency (fbEs) during the night (r=0.4 in both cases) as compared to the day (r=0.35 and -0.04, respectively). Furthermore, the signal strength of FAI is reasonably correlated with (ftEs-fbEs) during daytime (r=0.59) while very poorly correlated during nighttime (r=0.18). While the radar observations in general appear to have characteristics close to that of mid-latitudes, the relationship of these with the Es parameters are poorer than that of mid-latitudes. The observations reported here, nevertheless, are quite consistent with the expectations based on the gradient drift instability mechanism.

Mating and Oviposition of Tingis ampliata H.-S. (Het. Tingidae)

1973 ◽  
Vol 4 (4) ◽  
pp. 285-298 ◽  
Keyword(s):  
Dorsal Surface ◽  
Time Of Day ◽  
Oviposition Rate ◽  
Oviposition Period ◽  
Physical Conditions ◽  
Leaf Mesophyll ◽  
Total Fecundity ◽  
Average Fecundity ◽  
The Right ◽  
Peak Phase

AbstractPeriod of mating varies annually from 46 to 65 days during April to late June or early May to July. Lacebugs mated at any time of day but peak of pairing tended to occur about afternoon at field temperatures around I5°C. Duration of mating and angle between the sexes varies between pairs. In 55 % of pairs, males were to the right of females with dorsal surface of tip of male abdomen in contact with ventral aspect of that of female. Eggs are usually laid singly but occasionally in groups of 2-6 in thistle leaves. Oviposition in stems may occur at high adult densities in the laboratory. About 78-99 % of total eggs were laid in primary leaves, others in leaflets of axillary buds. Eggs were predominantly laid in midribs and other veins. Tingis eggs were implanted to varying degrees or seldom unembedded in leaf mesophyll with extrusion of part of chorion beyond non-oviposition surface in thin leaves. Oviposition rhythm was positively correlated with daily rhythm of physical conditions especially temperature. Six-hourly oviposition rate, proportion of females laying, and number of eggs laid per female increased from minimum between 00.00 and 06.00 hours to a peak at 12.00 to 18.00 hours and declined afterwards. Rate of oviposition and average fecundity varied annually according to temperature differential between pre-peak oviposition period of different years. Oviposition rate increased with temperature (in I965 and I966) and age (in I965) during pre-peak phase; but it decreased with aging of bugs in the post-peak phase when temperature had insignificant effects. Total fecundity in the laboratory or field varies considerably between individual females. At I5 and 20°C constant temperature, average numbers of eggs laid per female were 20 and 6I, respectively. Oviposition in laboratory tended to be periodic and females die without completing oviposition. Oviposition period varies annually in the field from I0 to I2 weeks, usually from early May to late July. In the laboratory this period varied with individuals and temperature from about 5.2 weeks at I5°C to at least 7.6 weeks at 20°C.

scholarly journals The Observations of Meteor Trail Made with Chung-Li VHF Radar

1990 ◽  
Vol 1 (2) ◽  
pp. 175
Author(s):  
Yen-Hsyang Chu ◽  
Tson-Ron Chian
Keyword(s):  
Vhf Radar ◽  
Meteor Trail

scholarly journals STRATEGI PERCEPATAN PEMBANGUNAN DAERAH BERBASIS KEARIFAN LOKAL DI KECAMATAN GUNUNG WUNGKAL

2018 ◽  
Vol 14 (1) ◽  
pp. 135
Author(s):  
Lailatis Syarifah
Keyword(s):  
Economic Development ◽  
Added Value ◽  
Educational Facilities ◽  
Physical Conditions ◽  
The Government ◽  
Tourism Potential ◽  
The Right

AbstractThis research aims to find out strategies that can be used to accelerate the pace of economic development in Gunungwungkal sub-district, by referring to physical, environmental, social and local wisdom conditions in Gunungwungkal in 2015. The result is that Gunungwungkal is a plateau with good physical conditions for agriculture and livestock but is constrained by the addition of added value in the production of goods. The number of residents of the productive age is more than the age of being unproductive, but the educational facilities are not sufficient, so other institutions such as training centers are needed. There is tourism potential such as Grojogan Sewu waterfall and monastery, but the infrastructure does not support it. Therefore, the right strategy to accelerate the development of the Gunungwungkal area is to increase the ability and knowledge of the population in order to provide added value to the production results and improve infrastructure, and this cannot be done except with good cooperation between the government and the community.

Sign in / Sign up

Export Citation Format

Share Document